This is how I generally read books, so there are dozens.
If you only count books I'm more than a couple chapters into, then in descending order of how long they've been on the list:
Gödel, Escher, Bach
Beelzebub's Tales to his Grandson
Finnegan's Wake
Gravity's Rainbow
House of Leaves
They're all great books, but they require a bit more dedicated reading time than I generally have.